A cyclist is coasting up a hill. At t=0, the cyclist has a velocity of 19.8 m/s. If the acceleration of cyclist is constant - 1.9m/s^2?
2017-07-15 10:50 am
How long will it take the cyclist to come to a complete stop? If the peak of the hill is 70 m away from the cyclist at t=0, will she have to pedal to reach the top?
回答 (1)
2017-07-15 11:45 am
Initial velocity, u = 19.8 m/s
Final velocity, v = 0
Acceleration, a = -1.9 m/s²
v = u + at
0 = 19.8 + (-1.9)t
Time taken, t = 10.4 s
v²= u² + 2as
0 = 19.8² + 2*(-1.9)s
Displacement, s = 103.3 m > 70 m
Hence, she needs not to pedal to reach the top.
Final velocity, v = 0
Acceleration, a = -1.9 m/s²
v = u + at
0 = 19.8 + (-1.9)t
Time taken, t = 10.4 s
v²= u² + 2as
0 = 19.8² + 2*(-1.9)s
Displacement, s = 103.3 m > 70 m
Hence, she needs not to pedal to reach the top.
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